Description:With a sly smirk, Stephen Colbert addressed the news that he's replacing David Letterman during Thursday's episode of The Colbert Report , joking, "I do not envy whoever they try to put in that chair. Colbert is set to take over the late-night spot after Letterman retires in 2015, and he's signed a five-year deal with CBS to host the show as himself, not the Colbert Report alter ego we've gotten to know on Comedy Central.(0:40)